“Never let a good crisis go to waste”, Winston Churchill is said to have proclaimed.

That humanity faces a serious climate crisis is no longer in doubt after the recent Concluding Instalment of the Fifth Assessment Report on Climate Change by the Intergovernmental Panel on Climate Change (IPCC), released in Copenhagen on 2 November. The good news from the report: this crisis also offers us the chance to create a ‘brighter and more sustainable future’. Provided, that is, that we implement stringent climate actions without any further delay.

Findings from over 830 scientists are the basis of the most comprehensive assessment of climate change ever undertaken. So what does the report say specifically about the implications of climate change on urban settlements?

The next two decades present a window of opportunity for mitigation in urban areas, as a large portion of the world’s urban areas will be developed during this period. Already today, urban areas account for more than half of global primary energy use and energy-related CO2 emissions, while containing a high proportion of the global population and economic activities. However, people and the economy are facing a number of risks from climate change, including heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scarcity, sea-level rise and storm surges. All of these lead to the destruction of homes, infrastructure and critical services, the disruption of livelihoods, and even deaths. These risks will be amplified for those lacking essential infrastructure and services, or living in exposed areas. Cities are therefore under the magnifying glass when it comes to climate action.

While cities can be the pioneers and driving forces of climate change efforts, they need support from other levels of government to be successful. Effective adaptation and mitigation responses will depend on policies and measures across multiple scales: international, regional, national and sub-national. The report highlights how policies across all scales supporting the development, diffusion and transfer of technology, as well as financial support for responses to climate change, can complement and enhance the effectiveness of policies that directly promote adaptation and mitigation. In addition, improving institutions as well as enhancing coordination and cooperation in governance is key to overcoming the regional constraints associated with mitigation, adaptation, and disaster risk reduction.

The report also highlights how international cooperation is critical. National governments play key roles in adaptation planning and implementation by coordinating actions and providing frameworks and support. While local government and the private sector have different functions, which vary regionally, they are increasingly recognized as critical to progress in adaptation, given their roles in scaling up adaptation of communities, households, and civil society.

On the issue of what is more important for effectively addressing climate change, the report states that, while adaptation is important, it is insufficient to limit the risks of climate change. Mitigation measures must substantially and sustainably reduce the volume and rate of greenhouse gas emissions, buying several decades of time for adaptation actions. Delaying additional mitigation to 2030 will significantly increase the technological, economic, social and institutional challenges associated with limiting warming over the twenty-first century to below 2 degrees Celsius relative to pre-industrial levels, the report finds.

Mitigation will not considerably hamper economic growth: the report estimates that the 1.6 to 3 percent per year growth rate in consumption (an indicator for economic growth) over the twenty-first century would be reduced by only around 0.06 percentage points, even with ambitious mitigation efforts. “Compared to the imminent risk of irreversible climate change impacts, the risks of mitigation are manageable”, was the assessment of Youba Sokona, Co-Chair of IPCC Working Group III. He also commented: “It is technically feasible to transition to a low-carbon economy, but what is lacking are appropriate policies and institutions. The longer we wait to take action, the more it will cost to adapt and mitigate climate change.”

There are already a lot of synergies and considerable progress. But there is still a lot to address – for instance, constraints concerning the implementation of effective climate action. The main issues are limited financial and human resources; limited integration or coordination of governance; uncertainties about projected impacts; different perceptions of risks; competing values; absence of key adaptation leaders and advocates; and limited tools to monitor adaptation effectiveness. These issues need to be addressed and tackled by all level of governments. The report underlines that policy linkages among regional, national, and sub-national climate policies actually offer potential climate change mitigation benefits, including lower mitigation costs, decreased emission leakage, and increased market liquidity.

“We have little time before the window of opportunity to stay within 2ºC of warming closes. To keep a good chance of staying below 2ºC, and at manageable costs, our emissions should drop by 40 to 70 percent globally between 2010 and 2050, falling to zero or below by 2100. We have that opportunity, and the choice is in our hands,” R. K. Pachauri, Chair of the IPCC, said.

According to scientists, an integrated response to urbanization can provide substantial opportunities for enhanced resilience, reduced emissions, and more sustainable development.

Mitigation strategies based on spatial planning and efficient infrastructure supply can avoid the lock-in of high emission patterns.

Mixed-use zoning, transport-oriented development, increased density, and co-located jobs and homes can reduce direct and indirect energy use across sectors.

Compact development of urban spaces and intelligent densification can preserve land carbon stocks and land for agriculture and bioenergy.

Reduced energy and water consumption in urban areas through greening cities and recycling water are examples of mitigation actions with adaptation benefits.

Building resilient infrastructure systems can reduce vulnerability of urban settlements and cities to coastal flooding, sea-level rise and other climate-induced stresses.

“We have the means to limit climate change,” said R. K. Pachauri. “The solutions are many and allow for continued economic and human development. All we need is the will to change, which we trust will be motivated by knowledge and an understanding of the science of climate change.” He also emphasizes that he hopes the report will “serve the needs of the world’s governments and provide the scientific basis to negotiators as they work towards a new global climate agreement.”